Pellet heads aren't round or correct size

[truck]

I measured five of each pellet at 90 degrees to the seams (when measured at the seams size is larger). I found all JSB's to be undersize and the Crosman to be nearest to correct size. All are domed pellets .177 caliber.

Crosman 10.5 gn.....................4.050 to 4.52
JSB 8.44 gn 4.53 head.............4.37 to 4.42
JSB 10.34 gn..........................4.43 to 4.47
JSB 7.87 gn............................4.43 to 4.45
JSB 8.44 gn 4.52 head.............4.41 to 4.45

The open end in the same order as above measured in thousandths.
.178
.183
.179
.181
.179

How on earth do drop in pellet gauges work with sizes like this?

EDIT.. sized changed to sizes

[Wayne52]

.177 pellets are the only ones that I can't cast yet because there's not a decent mold on the market yet.  For .22 and up there is and everything that I've cast so far has been very conssitent and they all seem to shoot excellent for my purpose's which are mainly hunting.  My best luck with pellets in .177 so far have been the 13.43 grain JSB's with the DAR177 which is set up for heavy stuff.  I never did try measuring them though but by the way they shoot they should be very consistent in size

[nervoustrigger]

You’re right. A go/no-go aperture gauge will simply sort by the larger dimension of an oval pellet.  This may still be of some benefit but only with pellet brands that have a lot of variation, and the results are seldom as good as unsorted pellets from a quality brand.  I had to arrive at that conclusion on my own however so I don’t want to dissuade you of the effort.  To this day I still engage in little experiments like tumble deburring pellets that have nasty parting lines and mold flashing.  Sometimes I’m rewarded with a substantial improvement but never equaling the best that a gun will do with its favorite batch of JSB/AA or H&N (or sometimes RWS) pellets.